Il 26/08/2014 11:21, Fam Zheng ha scritto:
> On Tue, 08/26 10:46, Paolo Bonzini wrote:
>> Il 26/08/2014 08:08, Fam Zheng ha scritto:
>>> + if (dbs->cancelled) {
>>> + ret = -ECANCELED;
>>> + }
>>
>> Why is dbs->cancelled necessary?
>
> Request may complete after bdrv_aio_cancel_async with other status, this flag
> is checked to fix the status to -ECANCELED.
Ah, that's because the operation could be partly incomplete?
I think it would be better to call dma_complete with -ECANCELED, instead
of doing the same dbs->cancelled check twice. For example, in dma_bdrv_cb:
if (dbs->sg_cur_index == dbs->sg->nsg || ret < 0) {
dma_complete(dbs, ret);
return;
}
if (dbs->cancelled) {
dma_complete(dbs, -ECANCELED);
return;
}
>>> +static void dma_aio_cancel_async(BlockDriverAIOCB *acb)
>>> +{
>>> + DMAAIOCB *dbs = container_of(acb, DMAAIOCB, common);
>>> +
>>> + trace_dma_aio_cancel(dbs);
>>> +
>>> + dbs->cancelled = true;
>>> + if (dbs->acb) {
>>> + acb = dbs->acb;
>>> + dbs->acb = NULL;
>>
>> Why do you need to set dbs->acb to NULL, since the callback is going to
>> be called?
>
> Just copied from dma_aio_cancel, but seems not particularly useful. It reminds
> me that the one in dma_aio_cancel also looks suspicious.
Yeah, that one looks useless too...
Paolo
